Hyper-Nastran接口视频教程之模态分析与瞬态分析

有限元分析类型一、nastran中的分析种类（1）静力分析静力分析是工程结构设计人员使用最为频繁的分析手段，主要用来求解结构在与时间无关或时间作用效果可忽略的静力载荷（如集中载荷、分布载荷、温度载荷、强制位移、惯性载荷等）作用下的响应、得出所需的节点位移、节点力、约束反力、单元内力、单元应力、应变能等。

该分析同时还提供结构的重量和重心数据。

（2）屈曲分析屈曲分析主要用于研究结构在特定载荷下的稳定性以及确定结构失稳的临界载荷，NX Nastran中的屈曲分析包括两类：线性屈曲分析和非线性屈曲分析。

（3）动力学分析NX Nastran在结构动力学分析中有非常多的技术特点，具有其他有限元分析软件所无法比拟的强大分析功能。

结构动力分析不同于静力分析，常用来确定时变载荷对整个结构或部件的影响，同时还要考虑阻尼及惯性效应的作用。

NX Nastran的主要动力学分析功能：如特征模态分析、直接复特征值分析、直接瞬态响应分析、模态瞬态响应分析、响应谱分析、模态复特征值分析、直接频率响应分析、模态频率响应分析、非线性瞬态分析、模态综合、动力灵敏度分析等可简述如下：❑正则模态分析正则模态分析用于求解结构的固有频率和相应的振动模态，计算广义质量，正则化模态节点位移，约束力和正则化的单元力及应力，并可同时考虑刚体模态。

❑复特征值分析复特征值分析主要用于求解具有阻尼效应的结构特征值和振型，分析过程与实特征值分析类似。

此外Nastran的复特征值计算还可考虑阻尼、质量及刚度矩阵的非对称性。

❑瞬态响应分析（时间-历程分析）瞬态响应分析在时域内计算结构在随时间变化的载荷作用下的动力响应，分为直接瞬态响应分析和模态瞬态响应分析。

两种方法均可考虑刚体位移作用。

直接瞬态响应分析该分析给出一个结构随时间变化的载荷的响应。

结构可以同时具有粘性阻尼和结构阻尼。

该分析在节点自由度上直接形成耦合的微分方程并对这些方程进行数值积分，直接瞬态响应分析求出随时间变化的位移、速度、加速度和约束力以及单元应力。

从hypermesh到nastran——模态和瞬态动力学分析鼓捣了几天终于行的通了，把自己的经验给大家分享一下。

模态分析关键步骤：1. 创建一个load collector, card image选择EIGRL(LANCZOS方法)。

2. 创建subcase，type为normal modes, method选中刚才创建的load collector。

3. 在control cards的sol选择nomal modes，param中选择autospec, 如果想生成op2文件，把post也选上4. 导出成bdf文件，启动nastran进行分析。

瞬态动力学分析如果激励是力比较好作，如果是强迫位移，老版本的需要用大质量或大刚度法把位移转换成力的载荷。

nastran 2001版以后可以直接加位移，关键步骤如下：1. 定义随时间历程曲线，创建load collectors，card image为Tabled12. 创建瞬态相应的时间步长和时间，load collectors, card image为Tstep3. 创建一个load collectors，card image为DAREA(如果是强迫位移不能用DAREA）4. 创建一个load collectors，card image为Tload1, excited选择DAREA，TID选择TSTEP，注意TYPE的选择。

5. 创建一个subcase，类型选择直接瞬态分析，DLOAD和TSTEP选择刚才创建的两个相对应的load collectors6. 导出成bdf文件，提交nastran进行分析。

如果是强迫位移，还要多两个卡，就是SPCD, LSEQ详细步骤跟以上差不多，只要把各个卡片弄懂了就很容易了。

有限元分析类型一、nastran中的分析种类（1）静力分析静力分析是工程结构设计人员使用最为频繁的分析手段，主要用来求解结构在与时间无关或时间作用效果可忽略的静力载荷（如集中载荷、分布载荷、温度载荷、强制位移、惯性载荷等）作用下的响应、得出所需的节点位移、节点力、约束反力、单元内力、单元应力、应变能等。

该分析同时还提供结构的重量和重心数据。

（2）屈曲分析屈曲分析主要用于研究结构在特定载荷下的稳定性以及确定结构失稳的临界载荷，NX Nastran中的屈曲分析包括两类：线性屈曲分析和非线性屈曲分析。

（3）动力学分析NX Nastran在结构动力学分析中有非常多的技术特点，具有其他有限元分析软件所无法比拟的强大分析功能。

结构动力分析不同于静力分析，常用来确定时变载荷对整个结构或部件的影响，同时还要考虑阻尼及惯性效应的作用。

NX Nastran的主要动力学分析功能：如特征模态分析、直接复特征值分析、直接瞬态响应分析、模态瞬态响应分析、响应谱分析、模态复特征值分析、直接频率响应分析、模态频率响应分析、非线性瞬态分析、模态综合、动力灵敏度分析等可简述如下：❑正则模态分析正则模态分析用于求解结构的固有频率和相应的振动模态，计算广义质量，正则化模态节点位移，约束力和正则化的单元力及应力，并可同时考虑刚体模态。

❑复特征值分析复特征值分析主要用于求解具有阻尼效应的结构特征值和振型，分析过程与实特征值分析类似。

此外Nastran的复特征值计算还可考虑阻尼、质量及刚度矩阵的非对称性。

❑瞬态响应分析（时间-历程分析）瞬态响应分析在时域内计算结构在随时间变化的载荷作用下的动力响应，分为直接瞬态响应分析和模态瞬态响应分析。

两种方法均可考虑刚体位移作用。

直接瞬态响应分析该分析给出一个结构随时间变化的载荷的响应。

结构可以同时具有粘性阻尼和结构阻尼。

该分析在节点自由度上直接形成耦合的微分方程并对这些方程进行数值积分，直接瞬态响应分析求出随时间变化的位移、速度、加速度和约束力以及单元应力。

目录一、软件介绍 (1)1.1 MSC.Patran介绍 (1)1.2 MSC.Nastran (2)二、翼板的模态分析 (3)2.1 建立几何模型的文件名 (4)2.2 创建几何模型 (4)2.3 划分有限元网格 (4)2.4 设置边界条件 (5)2.5定义材料属性 (5)2.6 定义单元属性 (6)2.7 进行分析 (7)2.8 查看分析结果 (7)2.8.1显示模态云图 (7)2.8.2显示模态变形图 (8)2.8.3同时显示模态云图及变形图 (8)三、平板颤振分析 (9)3.1结构建模 (10)3.2气动建模 (11)3.2.1设定气动参考坐标系 (11)3.2.2气动建模－网格划分 (11)3.3参数设置 (11)3.3.1参考弦长等参数设定 (11)3.3.2减缩频率等参数设定 (11)3.4耦合分析 (12)3.4.1生成样条 (12)3.4.2应用样条 (12)3.4.3设定工况、分析 (12)3.5结果分析 (13)四、总结 (14)五、参考文献 (14)一、软件介绍1.1 MSC.Patran介绍MSC.Patran(后称Patran)是一个集成的并行框架式有限元前后处理及分析仿真系统。

Patran最早由美国宇航局（NASA）倡导开发, 是工业领域最著名的并行框架式有限元前后处理及分析系统, 其开放式、多功能的体系结构可将工程设计、工程分析、结果评估、用户化设计和交互图形界面集于一身, 构成一个完整的CAE集成环境。

使用Patran, 可以帮助产品开发用户实现从设计到制造全过程的产品性能仿真。

Patran拥有良好的用户界面, 既容易使用又方便记忆。

Patran作为一个优秀的前后处理器, 具有高度的集成能力和良好的适用性, 具体表现在:1.模型处理智能化。

为了节约宝贵的时间, 减少重复建模, 消除由此带来的不必要的错误, Patran应用直接几何访问技术（DGA）, 能够使用户直接从一些世界先导的CAD/CAM系统中获取几何模型, 甚至参数和特征。

Normal Modes Analysis of a Splash Shield - RD-1020In this tutorial, an existing finite element model of an automotive splash shield will be used to demonstrate how to set up and perform a normal modes analysis. HyperMesh post-processing tools are used to determine mode shapes of the model.The following exercises are included:•Retrieving the RADIOSS input file•Setting up the model in HyperMesh•Applying Loads and Boundary Conditions to the Model•Submitting the job•Viewing the resultsStep 1: Launch HyperMesh and set the RADIOSS (Bulk Data) User Profileunch HyperMesh.A User Profiles… Graphic User Interface (GUI) will appear. If it does not appear, go to Preferences►User Profiles … from the menu on the top.2.Select RADIOSS in the User Profile dialog.3.From the extended list, select Bulk Data.4.Click OK.This loads the User Profile. It includes the appropriate template, macro menu, and import reader, paring down the functionality of HyperMesh to what is relevant for generating models in Bulk Data Format for RADIOSS and OptiStruct.Step 2: Import a Finite Element Model File in HyperMesh1.From the File pull-down menu on the toolbar, select Import….An Import… tab is added to your tab menu.2.Click to import an FE model.3.For the File type:, select RADIOSS (Bulk Data).4.Select the Files icon button.A Select RADIOSS (Bulk Data) file browser will pop up.5.Browse for sshield.fem file located in the HyperWorks installation directory under<install_directory>/tutorials/hwsolvers/radioss/ and select the file.6.Click Open►Import.7.Click Close to close the Import tab menu.Step 3: Review Rigid ElementsNotice there are two rigid "spiders" in the model. They are placed at locations where the shield is bolted down. This is a simplified representation of the interaction between the bolts and the shield. It is assumed that the bolts are significantly more rigid in comparison to the shield.The dependent nodes of the rigid elements have all six degrees of freedom constrained. Therefore, each "spider" connects nodes of the shell mesh together in such a way that they do not move with respect to one another.The following steps show how to review the properties of the rigid elements.1.From the 1D page, select the rigids.2.Click review.3.Select one of the rigid elements in the graphics region.In the graphics window, HyperMesh displays the IDs of the rigid element and the two end nodes and indicates the independent node with an 'I' and the dependent node with a 'D'. HyperMesh also indicates the constrained degrees of freedom for the selected element, through the dof checkboxes in the rigids panel. All rigid elements in this model should have all dofs constrained.4.Click return to go to the main menu.Step 4: Setting up the Material and Geometric PropertiesThe imported model has three component collectors with no materials. A material collector needs to be created and assigned to the shell component collectors. The rigid elements do not need to be assigned a material. Shell thickness values also need to be corrected.1.Select the Material Collectors toolbar button .2.Select the create subpanel using the radio buttons on the left-hand side of the panel.3.Click mat name = and enter steel.4.Select the desired color for the material steel by clicking on .5.Click card image = and select MAT1 from the pop-up menu.6.Click create/edit.The MAT1 card image pops up.7.For E, enter the value 2.0E5.8.For NU, enter the value 0.3.9.For RHO, enter the value 7.85E-9.If a quantity in brackets does not have a value below it, it is off. To change this, click the quantity in brackets and an entry field will appear below it. Click in the entry field, and a value can be entered.10.Click return.A new material, steel, has now been created. The material uses RADIOSS linear isotropic materialmodel, MAT1. This material has a Young's Modulus of 2E+05, a Poisson's Ratio of 0.3 and a material density of 7.85E-09. A material density is required for the normal modes solution sequence.At any time the card image for this collector can be modified using Card Editor.11.Click return to exit the Material Create panel.12.Select the Card Editor toolbar button .13.Click the down arrow on the right of the entity shown in the yellow box, select props from the extendedentity list.14.Click the yellow props button and then check the box next to design and nondesign.15.Click select.16.Make sure card image=is set to PSHELL.17.Click edit.The PSHELL card image for the design component collector pops up.18.Replace 0.300 in the T field with 0.25.19.Click return to save the changes to the card image.20.Click return to go to the main menu.Applying Loads and Boundary Conditions to the Model (Steps 5 - 7)The model is to be constrained using SPCs at the bolt locations, as shown in the following figure. The constraints will be organized into the load collector 'constraints'.To perform a normal modes analysis, a real eigenvalue extraction (EIGRL) card needs to be referenced in the subcase. The real eigenvalue extraction card is defined in HyperMesh as a load collector with an EIGRL card image. This load collector should not contain any other loads.Step 5: Create EIGRL card (to request the number of modes)If a quantity in brackets does not have a value below it, it is off. To change this, click on the quantity in brackets and an entry field will appear below it. Click on the entry field, and a value can be entered.Step 6: Create Constraints at Bolt LocationsSelecting nodes for constraining the bolt locations 1.Click the Load Collectors toolbar button .2.Select the create subpanel, using the radio buttons on the left-hand side of the panel.3.Click loadcol name = and enter EIGRL .4.Click card image= and select EIGRL from the pop-up menu.5.Click create/edit .6.For V2, enter the value 200.000.7.For ND , enter the value 6.8.Click return to save changes to the card image.1.Click loadcol name = and enter constraints .2.Click the switch next to card image and select no card image .3.Click create > return .4.From Analysis page, click the constraints panel and make sure that the createsubpanel is active.5.Select the two nodes, shown in the figure above, at the center of the rigid spiders, by clicking on them in the graphics window.6.Constrain all dofs with a value of 0.0.7.Click Load Type= and select SPC .8.Click createTwo constraints are created. Constraint symbols (triangles) appear in the graphics window at theselected nodes. The number 123456 is written beside the constraint symbol, if the label constraints is checked ‘ON’, indicating that all dofs are constrained.9.Click return to go the main menu.Step 7: Create a Load Step to perform Normal Modes Analysis1.From the Analysis page, enter the loadsteps panel.2.Click name = and enter bolted.3.Click the type: switch and select normal modes from the pop-up menu.4.Check the box preceding SPC.An entry field appears to the right of SPC.5.Click on the entry field and select constraints from the list of load collectors.6.Check the box preceding METHOD(STRUCT).An entry field appears to the right of METHOD.7.Click on the entry field and select EIGRL from the list of load collectors.8.Click create.A RADIOSS subcase has been created which references the constraints in the load collector constraintsand the real eigenvalue extraction data in the load collector EIGRL.9.Click return to go to the main menu.Submitting the JobStep 8: Running Normal Modes Analysis1.From the Analysis page, enter the RADIOSS panel.2.Click save as… following the input file:field.A Save file… browser window pops up.3.Select the directory where you would like to write the file and, in File name:, entersshield_complete.fem.4.Click Save.Note that the name and location of the sshield_complete.fem file shows in the input file: field.5.Set the export options:toggle to all.6.Click the run options: switch and select analysis.7.Set the memory options: toggle to memory default.8.Click Radioss.This launches the RADIOSS job.If the job was successful, new results files can be seen in the directory where the RADIOSS model file was written. The sshield_complete.out file is a good place to look for error messages that will help to debug the input deck if any errors are present.The default files written to your directory are:sshield_complete.html HTML report of the analysis, giving a summary of the problemformulation and the analysis results.sshield_complete.out RADIOSS output file containing specific information on the file setup, the set up of your optimization problem, estimates for the amountof RAM and disk space required for the run, information for eachoptimization iteration, and compute time information. Review this fileReview the Results using HyperViewEigenvector results are output by default, from RADIOSS for a normal modes analysis. This section describes how to view the results in HyperView.Step 9: Load the Model and Result Files into the Animation WindowIn this section, you will load a HyperView .h3d file into the HyperView animation window.HyperView is launched and the sshield_complete.h3d file is loaded.Step 10: View Eigen VectorsIt is helpful to view the deformed shape of a model to determine if the boundary conditions have been defined correctly and also to check if the model is deforming as expected. In this section, use the Deformed panel to review the deformed shape for last Mode .This means that the maximum displacement will be 10 modal units and all other displacements will be proportional.Using a scale factor higher than 1.0 amplifies the deformations while a scale factor smaller than 1.0 would reduce them. In this case, we are accentuating displacements in all directions.A deformed plot of the model overlaid on the original undeformed mesh is displayed in the graphics window. for warnings and errors.sshield_complete.h3dHyper 3D binary results file. sshield_complete.stat Summary of analysis process, providing CPU information for eachstep during analysis process. 1.Click the HyperView button in the RADIOSS panel. 2.Click Close to exit the Message Log menu that appears.1.Click on the switch next to the traffic light signaland select Modal .2.Select the Deformed toolbar button.3.Leave Result type:set to Eigen Mode (v).4.Set Scale: to Model units .5.Set Type: to Uniform and enter in a scale factor of 10 for Value:.6.Click Apply .7.Under Undeformed shape:, set Show: to Wireframe .8.From the Graphics pull-down menu, select Select Load Case to activate the Load Case andSimulation Selection dialog, as shown below.Step 11: A few points to be notedIn this analysis, it was assumed that the bolts were significantly stiffer than the shield. If the bolts needed to be made of aluminum and the shield was still made of steel, would the model need to be modified, and the analysis run again?It is necessary to push the natural frequencies of the splash shield above 50 Hz. With the current model, there should be one mode that violates this constraint: Mode 1. Design specifications allow the innerdisjointed circular rib to be modified such that no significant mass is added to the part. Is there a configuration for this rib within the above stated constraints that will push the first mode above 50 Hz? See tutorial OS-2020 to optimize rib locations for this part.Go ToRADIOSS, MotionSolve, and OptiStruct Tutorials9.Select Mode 6 - F=1.496557E+02 from the list and click OK to view Mode 6.10.To animate the mode shape, click the animation mode: modal.11.To control the animation speed, use the Animation Controls accessed with the director’s chair toolbar button .12.You could also review the rest of the mode shapes.。

基于HyperMesh与Nastran联合仿真引言随着科技的进步和工程领域的发展，仿真技术在工程设计和分析中扮演着越来越重要的角色。

HyperMesh和Nastran是两个在工程仿真中广泛应用的软件工具，它们的联合使用可以实现更精确和可靠的仿真结果。

本文将介绍基于HyperMesh与Nastran联合仿真的基本原理和使用方法，并通过案例分析来展示其在工程实践中的应用。

一、HyperMesh简介HyperMesh是由美国公司Altair Engineering开发的一款高性能有限元预处理软件。

它提供了一个功能强大而简洁的界面，能够帮助工程师快速准确地构建计算模型。

HyperMesh支持多种CAD格式的导入，并提供了丰富的网格划分和修改工具。

此外，HyperMesh还包含了一系列的仿真后处理功能，可以帮助用户对仿真结果进行可视化和分析。

二、Nastran简介Nastran是由美国公司NASA开发的一款经典的有限元分析软件。

它是目前工程仿真领域最常用的软件之一，可以广泛应用于结构、振动、热传导和流体力学等领域。

Nastran采用了成熟稳定的数值方法和高效快速的求解算法，能够准确地预测结构的运行和响应。

Nastran提供了一个强大的命令行界面，可以通过输入Nastran语句进行仿真模型的定义、材料属性的指定和边界条件的设置等。

三、HyperMesh与Nastran联合仿真原理HyperMesh与Nastran联合仿真的基本原理是将HyperMesh生成的几何模型转化为Nastran所需的有限元网格模型，并将该模型输入到Nastran求解器中进行仿真分析。

具体包括以下几个步骤：1.导入模型：将CAD模型导入HyperMesh中，并进行必要的几何处理和修正。

2.网格划分：使用HyperMesh提供的网格划分工具对模型进行网格划分，生成满足仿真要求的有限元网格。

3.材料属性和边界条件设置：通过HyperMesh进行材料属性的指定和边界条件的设置。

Nastran帮助文档D:\Program Files\nastran2010\md20101\Doc\pdf_nastran1、打开hypermesh选择nastran入口。

2、打开或导入响应模型（只是网格不带实体）。

3、点击material创建材料。

a)Type选择ISOTROPIC（各向同性）b)card image选择MAT1（Defines the material properties for linearisotropic materials.）nastran help文档。

c)点击creat/edit，编辑材料属性输入E（弹性模量）、NU（泊松比）、RHO（密度）。

由于各物理量之间都是相互关联的因此要注意单位的选择（详情见附件一）。

这里选择通用的E=2.07e5，NU=0.3，RHO=7.83e-9。

4、点击properties创建属性。

a)由于是二维模型type选择2D。

Card image选择PSHELL（壳单元）。

Material选择刚才新建的材料。

b)点击creat/edit。

c)定义厚度即T（例如T=3，注意此时单位是mm）。

5、创建material以及properties后要将这些数据赋予模型。

a)点击component。

b)由于不是创建是修改，所以左边点选update然后双击选择相应部件。

c)然后双击选择刚才新建的厚度属性。

d)最后点击update。

6、创建加载情况，点击。

a)加一个单位动态激励。

创建名为excite的激励，点击creat。

b)加载单位激励。

Analysis-constraints 确定加载力的方向。

例如X正方向加载激励，只需要勾选dof1，且值为1。

Load types选择DAREA。

然后在模型上选择一点，最后点击create。

c)创建激励频率范围。

创建名为tabled1，card image为TABLED1,点击creat/edit。

设置TABLED1_NUM=2，x(1)=0,y(1)=1,x(2)=1000,y(2)=1.d)创建rload2目的连接excite和tabled1.card image选择RLOAD2，点击creat/edit。